Camera, accessory apparatus, and their control methods

ABSTRACT

A camera is usable while a plurality of accessory apparatuses are connected to the camera. The camera includes a camera communication unit connected to a data communication channel used for a data communication between the camera and each of the plurality of accessory apparatuses, and a camera controller configured to perform the data communication with each of the plurality of accessory apparatuses via the data communication channel. The camera controller transmits to at least one sleep target accessory apparatus among the plurality of accessory apparatuses which is selected based on authentication information acquired from each of the plurality of accessory apparatuses, a sleep request command for shifting the sleep target accessory apparatus from an operation state for performing processing in response to a data transmission from the camera to a sleep state that does not perform the processing regardless of the data transmission.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of International Patent ApplicationNo. PCT/JP2018/037215, filed on Oct. 4, 2018, which claims the benefitof Japanese Patent Application No. 2017-211506, filed on Nov. 1, 2017,both of which are hereby incorporated by reference herein in theirentirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an image pickup (camera) system thatincludes a camera (image pickup apparatus; referred to as a camera bodyhereinafter) and an accessory apparatus, such as an interchangeable lensand an adapter, which can communicate with each other.

Description of the Related Art

In an interchangeable lens type camera system including a camera body towhich an interchangeable lens is detachably attachable, a communicationis performed for the camera body to control the operation of theinterchangeable lens and for the interchangeable lens to provide thecamera body with data necessary for its control and imaging. Inparticular, in imaging a recording use motion image and a live-viewdisplay use motion image with the interchangeable lens, a smooth lenscontrol is required at an imaging cycle, so it is necessary tosynchronize the imaging timing of the camera body and the control timingof the interchangeable lens with each other. Thus, the camera body needsto complete a data reception from the interchangeable lens and atransmission of a command, such as a variety of instructions andrequests, to the interchangeable lens within the imaging cycle. However,as a data amount received by the camera body from the interchangeablelens becomes larger or the imaging cycle becomes shorter (or the framerate becomes higher), a communication of a large amount of data athigher speed is required.

An adapter such as a wide converter or a teleconverter (extender) may beconnected between the camera body and the interchangeable lens, and thistype of adapter also communicates with the camera body similar to theinterchangeable lens. Hence, the camera system requires a communicationsystem in which the camera body can perform a one-to-many communicationwith a plurality of accessory apparatuses including the interchangeablelens and the adapter. As a communication method for realizing theone-to-many communication between a communication master and a pluralityof communication slaves, there is an I2C communication method disclosedin NXP materials: I2C bus specification and user manual Rev5.0J-2-Oct.9, 2012 [May 20, 2017 Internet search URL:http://www.nxp.com/documents/user_manual/UM10204_JA.pdf].

However, the address of the communication slave that can be specified bythe I2C bus is fixed for each communication slave or selected by theuser from a slight width (about several bits) by hardware. In any ofthese cases, the communication master needs to previously recognize theaddresses of a plurality of communication slaves connected to it.

On the other hand, in a camera system that can connect in series aplurality of accessory apparatuses as the communication slaves, thecamera body as the communication master may not previously know whattypes of accessory apparatuses and how many accessory apparatuses (suchas newly used ones) are connected. In this case, assume that addressesof 0 to n are assignable to the communication slaves. A camera body thatdoes not know type(s) and number of connected accessory apparatusesneeds to perform an authentication communication to authenticate(confirm) the accessory apparatus for all addresses from 0 to nincluding an address where no accessory apparatus exists. As a result,it takes a long time for the authentication communication, and the startof imaging by the camera system is delayed. At this time, if anaccessory apparatus is incompatible with the camera body (incompatibleaccessory apparatus) or a plurality of accessory apparatuses exceedingthe permissible number are connected to the camera body, malfunctions orcommunication failures of the image pickup system may occur.

SUMMARY OF THE INVENTION

The present invention provides an image pickup system capable ofavoiding a malfunction, a communication failure, and the like.

A camera according to one aspect of the present invention is usablewhile a plurality of accessory apparatuses are connected to the camera.The camera includes a camera communication unit connected to a datacommunication channel used for a data communication between the cameraand each of the plurality of accessory apparatuses, and a cameracontroller configured to perform the data communication with each of theplurality of accessory apparatuses via the data communication channel.The camera controller transmits to at least one sleep target accessoryapparatus among the plurality of accessory apparatuses through the datacommunication, a sleep request command for shifting the sleep targetaccessory apparatus from an operation state for performing processing inresponse to a data transmission from the camera to a sleep state thatdoes not perform the processing regardless of the data transmission.

An accessory apparatus according to another aspect of the presentinvention among a plurality of accessory apparatuses is connectable to acamera usable while the plurality of accessory apparatuses are connectedto the camera. The accessory apparatus includes an accessorycommunication unit connected to a data communication channel used for adata communication between the camera and each of the plurality ofaccessory apparatuses, and an accessory controller configured to performthe data communication with the camera via the data communicationchannel. When receiving a sleep request command from the camera via thedata communication, the accessory controller shifts from an operationstate for performing processing in response to a data transmission fromthe camera to a sleep state that does not perform the processingregardless of the data transmission.

A control method according to one aspect of the present invention isapplied to a camera usable while a plurality of accessory apparatusesare connected to the camera and configured to perform a datacommunication with each of the plurality of accessory apparatuses via adata communication channel. The control method includes the step ofcausing the camera to transmit to at least one sleep target accessoryapparatus among the plurality of accessory apparatuses through the datacommunication, a sleep request command for shifting the sleep targetaccessory apparatus from an operation state for performing processing inresponse to a data transmission from the camera to a sleep state thatdoes not perform the processing regardless of the data transmission.

A control method according to another aspect of the present invention isapplied to an accessory apparatus among a plurality of accessoryapparatuses connectable to a camera usable while the plurality ofaccessory apparatuses are connected to the camera, and configured toperform the data communication with the camera via the datacommunication channel. The control method includes the step of causingthe accessory apparatus to shift, when receiving a sleep request commandfrom the camera via the data communication, from an operation state forperforming processing in response to a data transmission from the camerato a sleep state that does not perform the processing regardless of thedata transmission.

A control program that is a computer program that causes a computer inthe camera or the accessory apparatus to operate in accordance with theabove control method also constitutes another aspect of the presentinvention.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a camera systemaccording to a first embodiment of the present invention.

FIG. 2 is a diagram showing communication circuits of a camera body(camera microcomputer), an interchangeable lens (lens microcomputer),and an adapter (adapter microcomputer) according to the firstembodiment.

FIG. 3 is a diagram showing a communication format according to thefirst embodiment.

FIG. 4 is a diagram showing communication waveforms in a broadcastcommunication according to the first embodiment.

FIG. 5 is a diagram showing communication waveforms in a P2Pcommunication according to the first embodiment.

FIG. 6 is a diagram showing communication waveforms when thecommunication mode is switched in the first embodiment.

FIG. 7A is a flowchart illustrating processing of the camera body in thebroadcast communication according to the first embodiment.

FIG. 7B is a flowchart showing processing of the interchangeable lensand the adapter in the broadcast communication according to the firstembodiment.

FIG. 8A is a flowchart illustrating processing of the camera body in theP2P communication according to the first embodiment.

FIG. 8B is a flowchart illustrating processing of the interchangeablelens and the adapter in the P2P communication according to the firstembodiment.

FIG. 9 is a diagram showing communication waveforms in authenticationcommunication processing according to the first embodiment.

FIG. 10 is a flowchart showing authentication communication processingaccording to the first embodiment.

FIG. 11 is a flowchart showing adapter sleep processing according to thefirst embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, a description will be givenof embodiments according to the present invention.

First Embodiment

FIG. 1 illustrates a configuration of an image pickup system (referredto as a camera system hereinafter) according to a first embodiment ofthe present invention that includes a camera (image pickup apparatus;referred to as a camera body hereinafter) 200, and an interchangeablelens 100 and an intermediate adapter apparatus (simply referred to as anadapter hereinafter) 300 as accessory apparatuses. This embodimentillustrates the camera body 200 usable while the interchangeable lens100 is connected via the adapter 300 (while a plurality of accessoryapparatuses are connected).

While FIG. 1 illustrates an illustrative camera system in which a singleadapter 300 is connected between the camera body 200 and theinterchangeable lens 100, a plurality of adapters may be connected inseries between the camera body 200 and the interchangeable lens 100.

The camera system according to this embodiment performs communicationsamong the camera body 200, the interchangeable lens 100, and the adapter300 using a plurality of communication methods. The camera body 200, theinterchangeable lens 100, and the adapter 300 transmit control commandsand data (information) through their respective communicators. Inaddition, each communicator supports a plurality of communicationmethods, and can select an optimal communication method in a variety ofsituations by switching to the common communication method insynchronization with each other according to the type of data to becommunicated and the purpose of communication.

A description will now be given of a more specific configuration of theinterchangeable lens 100, the camera body 200, and the adapter 300.

The interchangeable lens 100 and the adapter 300 are mechanically andelectrically connected via a mount 400 as a coupling mechanism.Similarly, the adapter 300 and the camera body 200 are mechanically andelectrically connected via a mount 401 as a coupling mechanism. Theinterchangeable lens 100 and the adapter 300 obtain the electric powerfrom the camera body 200 through power supply terminal portions (notshown) provided to the mounts 400 and 401. Then, the power is suppledwhich is necessary for operations of a variety of actuators, a lensmicrocomputer 111, and an adapter microcomputer 302 as described later.The interchangeable lens 100, the camera body 200, and the adapter 300communicate with each other through communication terminal portions(illustrated in FIG. 2) provided to the mounts 400 and 401.

The interchangeable lens 100 includes an image pickup optical system.The image pickup optical system includes, in order from an object OBJside, a field lens 101, a magnification varying lens 102 that changes amagnification, a diaphragm unit 114 that adjusts a light amount. Theimage pickup optical system further includes an image stabilization lens103 configured to reduce (correct) an image blur, and a focus lens 104used for focusing.

The zoom lens 102 and the focus lens 104 are held by lens holding frames105 and 106, respectively. The lens holding frames 105 and 106 aremovably guided in an optical axis direction (indicated by a broken linein the figure) by unillustrated guide shafts, and are driven in theoptical axis direction by stepping motors 107 and 108. The steppingmotors 107 and 108 move the zoom lens 102 and the focus lens 104 insynchronization with a driving pulse, respectively.

The image stabilization lens 103 shifts in a direction orthogonal to theoptical axis in the image pickup optical system to reduce image blurscaused by a camera shake such as a manual shake.

A lens microcomputer 111 serves as a lens controller (accessorycontroller) that controls the operation of each component in theinterchangeable lens 100. The lens microcomputer 111 receives a controlcommand and a transmission request command transmitted from the camerabody 200 via a lens communicator (accessory communicator) 112 includinga lens communication interface circuit. The lens microcomputer 111performs a lens control corresponding to the control command, andtransmits lens data corresponding to the transmission request command tothe camera body 200 via the lens communicator 112.

The lens microcomputer 111 outputs a driving signal to a zoom drivingcircuit 119 and a focus driving circuit 120 in response to a commandrelating to a magnification variation and focusing among the controlcommands to drive the stepping motors 107 and 108. This configurationcan provide zoom processing for controlling the magnification varyingoperation with the zoom lens 102 and AF (autofocus) processing forcontrolling the focusing operation with the focus lens 104.

The diaphragm unit 114 includes aperture blades 114 a and 114 b. Thestates (positions) of the aperture blades 114 a and 114 b are detectedby a Hall element 115. The output from the Hall element 115 is input tothe lens microcomputer 111 via an amplifier circuit 122 and an A/Dconversion circuit 123. The lens microcomputer 111 outputs a drivingsignal to a diaphragm driving circuit 121 based on an input signal fromthe A/D conversion circuit 123 to drive a diaphragm actuator 113.Thereby, a light amount adjustment operation by the diaphragm unit 114is controlled.

The lens microcomputer 111 controls an image stabilization actuator(voice coil motor etc.) 126 via an image stabilization driving circuit125 in accordance with the camera shake detected by a shake sensor (notshown) such as a vibration gyro provided in the interchangeable lens100. Thereby, the image stabilization processing for controlling theshift operation (image stabilization operation) of the imagestabilization lens 103 is performed.

The interchangeable lens 100 includes a manual operation ring (simplyreferred to as an operation ring hereinafter) 130 and an operation ringdetector 131. The operation ring detector 131 includes, for example, twophoto-interrupters that output two-phase signals in accordance with arotation of the operation ring 130. The lens microcomputer 111 candetect the rotational operation amount of the operation ring 130. Thelens microcomputer 111 can notify the camera microcomputer 205 of therotational operation amount of the operation ring 130 via the lenscommunicator 112.

The adapter 300 includes, for example, an extender for changing a focallength, and includes a magnification varying lens 301 and an adaptermicrocomputer 302. The adapter microcomputer 302 is an adaptercontroller (accessory controller) that controls the operation of eachcomponent in the adapter 300. The adapter microcomputer 302 receives acontrol command and a transmission request command transmitted from thecamera body 200 via an adapter communicator (accessory communicator) 303including a communication interface circuit. The adapter microcomputer302 performs an adapter control corresponding to the control command,and transmits adapter data corresponding to the transmission requestcommand to the camera body 200 via the adapter communicator 303.

The camera body 200 includes an image sensor 201, such as a CCD sensoror a CMOS sensor, an A/D conversion circuit 202, a signal processingcircuit 203, a recorder 204, a camera microcomputer 205, and a displayunit 206.

The image sensor 201 photoelectrically converts an object image formedby the image pickup optical system in the interchangeable lens 100 andoutputs an electrical signal (analog signal). The A/D conversion circuit202 converts the analog signal from the image sensor 201 into a digitalsignal. The signal processing circuit 203 performs various types ofimage processing for the digital signal from the A/D conversion circuit202 and generates an image signal. The signal processing circuit 203also generates, from the image signal, focus information indicating acontrast state of an object image (focus state of the image pickupoptical system) and luminance information indicating an exposure state.The signal processing circuit 203 outputs the image signal to thedisplay unit 206, and the display unit 206 displays the image signal asa live-view image used for a confirmation of a composition, a focusstate, etc.

A camera microcomputer 205 as a camera controller controls the camerabody 200 in accordance with an input from a camera operation member,such as an unillustrated imaging instructing switch and a variety ofsetting switches. The camera microcomputer 205 transmits a controlcommand relating to the magnification varying operation of the zoom lens102 to the lens microcomputer 111 in accordance with the operation of anunillustrated zoom switch via the camera communicator 208 including thecommunication interface circuit. Moreover, the camera microcomputer 205transmits, to the lens microcomputer 111 via the camera communicator208, a control command relating to the light amount adjustment operationof the diaphragm unit 114 in accordance with the luminance informationand the focusing operation of the focus lens 104 in accordance with thefocus information. The camera microcomputer 205 transmits a transmissionrequest command for acquiring the control information and statusinformation of the interchangeable lens 100 to the lens microcomputer111, if necessary. Further, the camera microcomputer 205 transmits tothe adapter microcomputer 302 a transmission request command foracquiring the control information and status information of the adapter300.

Referring now to FIG. 2, a description will be given of a communicationcircuit configured among the camera body 200 (camera microcomputer 205),the interchangeable lens 100 (lens microcomputer 111), and the adapter300 (adapter microcomputer 302). The camera microcomputer 205, the lensmicrocomputer 111, and the adapter microcomputer 302 achievecommunications using signal lines connected via communication terminalportions provided on the mounts 400 and 401.

The signal lines include a signal line (first signal line correspondingto a signal transmission channel) CS that communicates a signal for acommunication control, and a signal line (second signal corresponding toa data communication channel) DATA for a data communication.

The signal line CS is connected to the camera microcomputer 205, theadapter microcomputer 302, and the lens microcomputer 111. Therefore,the camera microcomputer 205, the adapter microcomputer 302, and thelens microcomputer 111 can detect high and low levels of the state ofthe signal line CS. The signal line CS is pulled up to an unillustratedpower source in the camera body 200. The signal line CS can be connectedto a ground GND (open drain connection) via a ground switch 1121 in theinterchangeable lens 100, a ground switch 2081 in the camera body 200,and a ground switch 3031 in the adapter 300.

Due to this configuration, the camera microcomputer 205, the adaptermicrocomputer 302, and the lens microcomputer 111 can put the signalline CS into low by turning on (connecting) the ground switches 2081,1121, and 3031, respectively. In addition, the camera microcomputer 205,the adapter microcomputer 302, and the lens microcomputer 111 can putthe signal line CS into high by turning off (disconnect) the groundswitches 2081, 1121, and 3031, respectively. Furthermore, a CS switch(channel switch) 3033 is provided in the adapter 300. The adaptermicrocomputer 302 can connect and disconnect the signal line CS byswitching the CS switch 3033 between the connected state and thedisconnected state. In the disconnected state of the CS switch 3033, thesignal output state from the camera side (camera body 200 in thisembodiment) of the adapter 300 to the signal line CS and the signaloutput state from the adapter 300 to the signal line CS are nottransmitted to the interchangeable lens side (interchangeable lens 100in this embodiment). In other words, the broadcast communicationdescribed later is unavailable from the adapter 300 to the communicationslave on the interchangeable lens side.

A detailed description will be given later of a communication controlsignal (instruction or notification) transmitted through the signal lineCS and its output processing.

The signal line DATA is a single-wire bidirectional data communicationline that can be used by switching the data transmission direction. Thesignal line DATA is connectable to the lens microcomputer 111 via aninput/output switch 1122 in the interchangeable lens 100, andconnectable to the camera microcomputer 205 via an input/output switch2082 in the camera body 200. The signal line DATA is connectable to theadapter microcomputer 302 via an input/output switch 3032 in the adapter300. Each microcomputer includes a CMOS type data output part fortransmitting data and a CMOS type data input part for receiving data(none of which is shown). Each microcomputer can select whether thesignal line DATA is connected to the data output part or the data inputpart, by switching the input/output switch.

Each of the camera microcomputer 205, the adapter microcomputer 302, andthe lens microcomputer 111 when transmitting data sets the input/outputswitch so as to connect the signal line DATA to the data output part.Each of the camera microcomputer 205, the adapter microcomputer 302, andthe lens microcomputer 111 when receiving data sets an input/outputswitch so as to connect the signal line DATA to the data input part.Details of the input/output switching processing of the signal line DATAwill be described later.

FIG. 2 illustrates an illustrative communication circuit, but anothercommunication circuit may be used. For example, the signal line CS maybe pulled down to GND in the camera body 200 and connected to anunillustrated power supply via the ground switch 1121 in theinterchangeable lens 100, the ground switch 2081 in the camera body 200,and the ground switch 3031 in the adapter 300. In the interchangeablelens 100, the camera body 200, and the adapter 300, the signal line DATAmay be always connected to the data input part, and the connection anddisconnection between the signal line DATA and the data output part maybe selected by a switch.

[Communication Data Format]

Referring now to FIG. 3, a description will be given of a format ofcommunication data exchanged among the camera body 200 (cameramicrocomputer 205), the interchangeable lens 100 (lens microcomputer111), and the adapter 300 (adapter microcomputer 302). Thiscommunication data format is common to the broadcast communication,which is a first communication described later, and the P2Pcommunication, which is a second communication. A description will nowbe given of a communication data format in a so-called asynchronouscommunication in which a communication speed used for a communicationamong the microcomputers are previously determined and the transmissionand reception are performed at a communication bit rate in accordancewith the protocol.

Initially, in a non-transmission state that transmits no data, thesignal level is maintained high. Next, in order to notify the datareception side of a start of the data transmission, the signal level isset to be low for one bit period. This one bit period will be referredto as a start bit ST. Next, one-byte data is transmitted for aneight-bit period from the next second bit to the ninth bit. The bitarrangement of the data starts with the most significant data D7 in theMSB first format, continues with data D6, data D5, . . . , Data D1, andends with the least significant data D0. In the tenth bit, one-bitparity PA information is added, and one frame level starting from thestart bit ST is completed by finally putting the signal level into highduring a stop bit SP period indicating the end of the transmission data.

FIG. 3 illustrates an illustrative communication data format, butanother communication data format may be used. For example, the bitarrangement of the data may be the LSB first or the nine-bit length, orno parity PA information need not be added. The communication dataformat may be switched between broadcast communication and the P2Pcommunication.

[Broadcast Communication]

Next follows a description of the broadcast communication (firstcommunication). The broadcast communication is the one-to-manycommunication in which one of the camera microcomputer 205, the lensmicrocomputer 111, and the adapter microcomputer 302 transmits data tothe other two at the same time (i.e., simultaneous transmission). Thisbroadcast communication is performed using the signal line CS and thesignal line DATA. A communication mode in which the broadcastcommunication is performed is also referred to as a broadcastcommunication mode (first communication mode).

FIG. 4 illustrates signal waveforms in the broadcast communication amongthe camera microcomputer 205, the lens microcomputer 111, and theadapter microcomputer 302. Here is an example in which the adaptermicrocomputer 302 performs the broadcast communication to the cameramicrocomputer 205 and the lens microcomputer 111 in response to thebroadcast communication from the camera microcomputer 205 to the lensmicrocomputer 111 and the adapter microcomputer 302.

Initially, the camera microcomputer 205 as a communication master startsthe low output to the signal line CS in order to notify the lensmicrocomputer 111 and the adapter microcomputer 302 as communicationslaves that the broadcast communication is to be started. Next, thecamera microcomputer 205 outputs data to be transmitted, to the signalline DATA. On the other hand, the lens microcomputer 111 and the adaptermicrocomputer 302 start the low output to the signal line CS whendetecting the start bit ST input from the signal line DATA. At thistime, since the camera microcomputer 205 has already started the lowoutput to the signal line CS, the signal level of the signal line CSdoes not change.

Thereafter, the camera microcomputer 205 stops the low output to thesignal line CS after the stop bit SP is output. On the other hand, afterreceiving the stop bit SP input from the signal line DATA, the lensmicrocomputer 111 and the adapter microcomputer 302 analyze the receiveddata and perform internal processing associated with the received data.When the preparation for receiving the next data is completed, the lowoutput to the signal line CS is stopped. As described above, the signallevel of the signal line CS becomes high when all of the cameramicrocomputer 205, the lens microcomputer 111, and the adaptermicrocomputer 302 stop the low output to the signal line CS. Thus, eachof the camera microcomputer 205, the lens microcomputer 111, and theadapter microcomputer 302 can confirm that the signal level of thesignal line CS becomes high after stopping the low output to the signalline CS. When each of the camera microcomputer 205, the lensmicrocomputer 111, and the adapter microcomputer 302 confirms that thesignal level of the signal line CS has become high, it can determinethat the current communication processing is completed and it is readyfor the next communication.

Next, when confirming that the signal level of the signal line CS hasreturned to the high level, the adapter microcomputer 302 starts the lowoutput to the signal line CS in order to notify the camera microcomputer205 and the lens microcomputer 111 that the broadcast communication isto be started.

Next, the adapter microcomputer 302 outputs the data to be transmitted,to the signal line DATA. The camera microcomputer 205 and the lensmicrocomputer 111 start the low output to the signal line CS whendetecting the start bit ST input from the signal line DATA. Since theadapter microcomputer 302 has already started the low output to thesignal line CS at this time, the signal level propagated to the signalline CS does not change. Thereafter, the adapter microcomputer 302 stopsthe low output to the signal line CS when it completes outputting thestop bit SP. On the other hand, after receiving up to the stop bit SPinput from the signal line DATA, the camera microcomputer 205 and thelens microcomputer 111 analyze the received data and perform internalprocessing associated with the received data. Then, after thepreparation for receiving the next data is completed, the low output tothe signal line CS is stopped.

As described above, the signal transmitted through the signal line CS inthe broadcast communication serves as a signal indicating the start(execution) and the ongoing execution of the broadcast communication.

FIG. 4 illustrates an illustrative broadcast communication, but anotherbroadcast communication may be performed. For example, the datatransmitted in a single broadcast communication may be one-byte data asillustrated in FIG. 4, but may be two-byte or three-byte data. Thebroadcast communication may be a one-way communication from the cameramicrocomputer 205 serving as a communication master to the lensmicrocomputer 111 and adapter microcomputer 302 serving as communicationslaves.

[P2P Communication]

Next follows a description of the P2P communication performed among thecamera body 200 (camera microcomputer 205), the interchangeable lens 100(lens microcomputer 111), and the adapter 300 (adapter microcomputer302). The P2P communication is a one-to-one communication (individualcommunication) in which the camera body 200 as the communication masterdesignates (selects) a single communication counterpart (specificaccessory apparatus) among the interchangeable lens 100 and the adapter300 as the communication slaves, and communicates data with only thedesignated communication slave. This P2P communication is also performedusing the signal line CS and the signal line DATA. A communication modein which the P2P communication is performed will be also referred to asa P2P communication mode (second communication mode).

FIG. 5 illustrates, in an example, signal waveforms of the P2Pcommunication exchanged between the camera microcomputer 205 and thelens microcomputer (specific accessory apparatus) 111 designated as thecommunication counterpart. In response to one-byte data transmissionfrom the camera microcomputer 205, the lens microcomputer 111 transmitstwo-byte data to the camera microcomputer 205. Communication modeswitching processing (between the broadcast communication mode and theP2P communication mode) and processing for designating the communicationcounterpart in the P2P communication will be described later.

Initially, the camera microcomputer 205 as the communication masteroutputs data to be transmitted to the lens microcomputer 111, to thesignal line DATA. The camera microcomputer 205 starts the low output(standby request) to the signal line CS after completing the output ofthe stop bit SP. After the camera microcomputer 205 is ready to receivethe next data, the camera microcomputer 205 stops the low output to thesignal line CS. On the other hand, after detecting the low signal inputfrom the signal line CS, the lens microcomputer 111 analyzes thereceived data input from the signal line DATA and performs internalprocessing associated with the received data. Thereafter, whenconfirming that the signal level of the signal line CS has returned tothe high level, the lens microcomputer 111 continuously outputs two-bytedata to be transmitted, to the signal line DATA.

The lens microcomputer 111 starts the low output to the signal line CSafter completing the output of the stop bit SP of the second byte.Thereafter, when becoming ready to receive the next data, the lensmicrocomputer 111 stops the low output to the signal line CS. Theadapter microcomputer 302 that is not designated as the communicationcounterpart for the P2P communication does not output the signal to thesignal line CS or the signal line DATA.

As described above, the signal transmitted through the signal line CS inthe P2P communication serves as a notification signal indicating the endof the data transmission and a standby request for the next datatransmission.

While FIG. 5 illustrates the illustrative P2P communication, another P2Pcommunication may be used. For example, data may be transmitted everyone byte at a time using the signal line DATA, or data may betransmitted every three bytes or more.

[Communication Mode Switching Processing and Communication CounterpartDesignating Processing]

Referring now to FIG. 6, a description will be given of thecommunication mode switching processing and the communicationcounterpart designating processing in the P2P communication. FIG. 6illustrates signal waveforms during the communication mode switching andcommunication counterpart designating, which are exchanged among thecamera microcomputer 205, the lens microcomputer 111, and the adaptermicrocomputer 302. The communication counterpart of the P2Pcommunication is designated by the broadcast communication. In thisillustrative description, the adapter microcomputer 302 is designated asthe communication counterpart of the P2P communication by the cameramicrocomputer 205, and one-byte data P2P communication from the cameramicrocomputer 205 and one-byte data P2P communication from the adaptermicrocomputer 302 are executed. Thereafter, the lens microcomputer 111is designated as the communication counterpart of the P2P communicationby the camera microcomputer 205, and two-byte data P2P communicationfrom the camera microcomputer 205 and three-byte data P2P communicationfrom the lens microcomputer 111 are executed.

Initially, the camera microcomputer 205 which is the communicationmaster executes the broadcast communication according to the proceduredescribed in FIG. 4. What is notified by this broadcast communication isslave designation data for designating the communication counterpartwith the camera microcomputer 205 in the next P2P communication. Thelens microcomputer 111 and the adapter microcomputer 302, which are thecommunication slaves at this time, determine whether or not they aredesignated as the communication counterpart in the P2P communicationbased on the slave designation data received by the broadcastcommunication. This determination result switches the communicationmodes of the camera microcomputer 205 and the designated communicationslave (specific accessory apparatus) from the broadcast communicationmode to the P2P communication mode. Since the adapter microcomputer 302is designated herein as the communication counterpart in the next P2Pcommunication, data is transmitted and received between the cameramicrocomputer 205 and the adapter microcomputer 302 in accordance withthe procedure described in FIG. 5. Herein, one-byte data is transmittedfrom the camera microcomputer 205 to the adapter microcomputer 302, andthen one-byte data is transmitted from the adapter microcomputer 302 tothe camera microcomputer 205.

When the P2P communication ends between the camera microcomputer 205 andthe adapter microcomputer 302, the camera microcomputer 205 can againdesignate a communication counterpart for the P2P communication by thebroadcast communication. Herein, in order to designate the lensmicrocomputer 111 as the communication counterpart for the next P2Pcommunication, the lens microcomputer 111 is set to the slavedesignation data, and the broadcast communication is executed accordingto the procedure described in FIG. 4. In response to this broadcastcommunication, the adapter microcomputer 302 ends the P2P communication,and at the same time, the communication modes of the cameramicrocomputer 205 and the lens microcomputer 111 are switched to the P2Pcommunication mode. If no broadcast communication is executed at thisstage, the P2P communication continues between the camera microcomputer205 and the adapter microcomputer 302.

In the next P2P communication, data is transmitted and received betweenthe camera microcomputer 205 and the lens microcomputer 111 inaccordance with the procedure described in FIG. 5. Herein, the cameramicrocomputer 205 transmits two-byte data to the lens microcomputer 111,and then the lens microcomputer 111 transmits three-byte data to thecamera microcomputer 205.

As described above, the broadcast communication can designate thecommunication counterpart for the P2P communication, and at the sametime, and the broadcast communication and the P2P communication can beswitched.

[Communication Control Processing]

A description will now be given of communication control processingperformed among the camera microcomputer 205, the lens microcomputer111, and the adapter microcomputer 302. Referring now to the flowchartin FIGS. 7A and 7B, a description will be given of processing in thebroadcast communication mode. FIG. 7A illustrates processing performedby the camera microcomputer 205, and FIG. 7B illustrates processingperformed by the lens microcomputer 111 and the adapter microcomputer302. Each of the camera microcomputer 205, the lens microcomputer 111,and the adapter microcomputer 302, each of which includes the computer,executes this processing and other processing described later inaccordance with a communication control program as a computer program.

When an event for starting the broadcast communication occurs in thestep S100, the camera microcomputer 205 turns on (connects) the groundswitch 2081 to put the signal line CS into low in the step S101.Thereby, the start of the broadcast communication is notified to thelens microcomputer 111 and the adapter microcomputer 302. The lensmicrocomputer 111 and the adapter microcomputer 302 that have detectedthe low level of the signal line CS in the step S200 permit the datareception from the signal line DATA in the step S201.

Next, the camera microcomputer 205 operates the input/output switch 2082in the step S102 to connect the signal line DATA to the data outputpart, and performs the data transmission in the step S103. Whendetecting the start bit of the signal line DATA in the step S202, thelens microcomputer 111 and the adapter microcomputer 302 turns on(connects) the lens switch 1121 and the ground switch 3031 so as toindicate the ongoing communication processing in the step S205. Thereby,the low output to the signal line CS starts. Thereafter, whendetermining that all data has been received in the step S206, the lensmicrocomputer 111 and the adapter microcomputer 302 prohibit the datareception from the signal line DATA in the step S207. Further, in thestep S208, the ground switch 1121 and the ground switch 3031 are turnedoff (disconnected) to indicate that the communication processing hasended, and the low output to the signal line CS is stopped. Herein, thenumber of bytes of data to be transmitted and received is not limited,as long as the camera microcomputer 205, the lens microcomputer 111, andthe adapter microcomputer 302 has common recognitions.

Next, in the step S104, the camera microcomputer 205 determines whetherthe data transmitted in the step S103 is a bidirectional commandincluding the transmission from the lens microcomputer 111 or theadapter microcomputer 302. If data is not the bidirectional command, thecamera microcomputer 205 turns off (disconnects) the ground switch 2081in the step S105 to stop the low output to the signal line CS, andproceeds to the step S116. If it is the bidirectional command, thecamera microcomputer 205 operates the input/output switch 2082 in thestep S106 to connect the signal line DATA to the data input part. In thestep S107, the ground switch 2081 is turned off (disconnects) to stopthe low output to the signal line CS, and it waits for the signal lineCS to become high in the step S108.

On the other hand, in the step S209, the lens microcomputer 111 and theadapter microcomputer 302 determine whether the data received in thestep S206 is the bidirectional command including the transmission fromitself. If the data is not the bidirectional command, the lensmicrocomputer 111 and the adapter microcomputer 302 proceed to the stepS215, and if the data is the bidirectional command, the lensmicrocomputer 111 and the adapter microcomputer 302 wait for the signalline CS to become high in the step S210. When the signal line CS becomeshigh, the lens microcomputer 111 and the adapter microcomputer 302notify the start of the broadcast communication by turning on(connecting) the ground switches 1121 and 3031 and by putting the signalline CS into low in the step S211. When detecting the low level of thesignal line CS in the step S109, the camera microcomputer 205 permitsthe data reception from the signal line DATA in the step S110.

Next, the lens microcomputer 111 and the adapter microcomputer 302operate the input/output switches 1122 and 3032 in the step S212 toconnect the signal line DATA to the data output part, and perform thedata transmission in the step S213. When detecting the start bit of thesignal line DATA in the step S111, the camera microcomputer 205 turns on(connects) the ground switch 2081 to indicate ongoing communicationprocessing in the step S112. Thereby, the low output to the signal lineCS starts. The lens microcomputer 111 and the adapter microcomputer 302stop the low output to the signal line CS by turning off (disconnecting)the ground switches 1121 and 3031 in the step S214 after thetransmissions of all data are completed.

If the camera microcomputer 205 determines that all data has beenreceived in the step S113, it prohibits the data reception from thesignal line DATA in the step S114. In the step S115, the cameramicrocomputer 205 turns off (disconnects) the ground switch 2081 to stopthe low output to the signal line CS in order to indicate that thecommunication processing has ended. Herein, the number of bytes of datato be transmitted and received is not limited, as long as the cameramicrocomputer 205, the lens microcomputer 111, and the adaptermicrocomputer 302 have common recognitions.

Next, the camera microcomputer 205 waits for the signal line CS tobecome high in the step S116. When the signal line CS becomes high, thecamera microcomputer 205 determines in the step S117 whether or not thelens microcomputer 111 or the adapter microcomputer 302 has beendesignated as a communication counterpart for the P2P communicationbased on the data transmitted in the step S103. If none of the lensmicrocomputer 111 and the adapter microcomputer 302 are designated asthe communication counterparts, the camera microcomputer 205 ends theprocessing as it is, and if any is designated, the camera microcomputer205 transfers to the P2P communication mode in the step S118.

On the other hand, the lens microcomputer 111 and the adaptermicrocomputer 302 stand by until the signal line CS becomes high in thestep S215. When the signal line CS becomes high, in the step S216, thelens microcomputer 111 and the adapter microcomputer 302 determinewhether or not they are designated as the communication counterpart forthe P2P communication by the camera microcomputer 205, based on the datareceived in the step S206. If none of the lens microcomputer 111 and theadapter microcomputer 302 are designated as the communicationcounterparts, the processing ends. If it is designated as thecommunication counterpart, the designated microcomputer out of the lensmicrocomputer 111 and the adapter microcomputer 302 permits the datareception from the signal line DATA in the step S217, and transfers tothe P2P communication mode in the step S218.

If the start bit is not detected in the step S202, the lensmicrocomputer 111 and the adapter microcomputer 302 confirm whether ornot the signal line CS has become high in the step S203. When the signalline CS becomes high (returns to the high level), the lens microcomputer111 and the adapter microcomputer 302 prohibit the data reception fromthe signal line DATA in the step S204 and end the processing. This isprocessing for a communication slave not designated as a communicationcounterpart for the P2P communication to respond to the low output tothe signal line CS by the P2P communication between the cameramicrocomputer 205 and another communication slave.

Referring now to flowcharts in FIGS. 8A and 8B, a description will begiven of processing in the P2P communication mode. FIG. 8A illustratesprocessing performed by the camera microcomputer 205, and FIG. 8Billustrates processing performed by a microcomputer (referred to as aspecific microcomputer hereinafter) designated as a communicationcounterpart for the P2P communication among the lens microcomputer 111and the adapter microcomputer 302.

When an event for starting the P2P communication occurs in the stepS300, the camera microcomputer 205 operates the input/output switch 2082in the step S301 to connect the signal line DATA to the data outputpart, and performs the data transmission in the step S302. Thereafter,when all data transmissions are completed, the camera microcomputer 205turns on (connects) the ground switch 2081 in the step S303 and startsthe low output to the signal line CS. On the other hand, when thespecific microcomputer detects the low level of the signal line CS inthe step S400, it determines that the data transmission from the cameramicrocomputer 205 is completed, and analyzes the data received from thesignal line DATA in the step S401.

Next, in the step S304, the camera microcomputer 205 determines whetherthe data transmitted in the step S302 is the bidirectional commandincluding the transmission from the specific microcomputer. If it is notthe bidirectional command, the camera microcomputer 205 turns off(disconnects) the ground switch 2081 in the step S305 to stop the lowoutput to the signal line CS. In the step S306, it waits for the signalline CS to become high before proceeding to the step S311. If the datais the bidirectional command, the camera microcomputer 205 operates theinput/output switch 2082 in the step S307 to connect the signal lineDATA to the data input part. In the step S308, the ground switch 2081 isturned off (disconnected) to stop the low output to the signal line CS.

On the other hand, after waiting for the high level of the signal lineCS in the step S402, the specific microcomputer determines in the stepS403 whether the data received in the step S401 is the bidirectionalcommand including the transmission from itself. If it is not thebidirectional command, the specific microcomputer turns on (connects)and turns off (disconnects) the ground switch (1121 or 3031) in thesteps S404 and S405. Thereby, the low output to the signal line CS isstarted and stopped, and the flow proceeds to the step S411. In thebidirectional command, the specific microcomputer operates theinput/output switch (1122 or 3032) in the step S406 to connect thesignal line DATA to the data output part, and performs the datatransmission in the step S407. Thereafter, when all data transmissionsare completed, the specific microcomputer starts the low output to thesignal line CS by turning on (connecting) the ground switch (1121 or3031) in the step S408.

Next, when detecting the low level in the signal line CS in the stepS609, the camera microcomputer 205 determines in the step S310 that thedata transmission from the specific microcomputer has been completed,and analyzes the data received from the signal line DATA. On the otherhand, in the step S409, the specific microcomputer operates theinput/output switch (1122 or 3032) to connect the signal line DATA tothe data input part. Thereafter, the specific microcomputer turns off(disconnects) the ground switch (1121 or 3031) in the step S410 to stopthe low output to the signal line CS.

Next, the camera microcomputer 205 waits for the signal line CS tobecome high in the step S311. Thereafter, when an event for starting thebroadcast communication occurs in the step S312, the cameramicrocomputer 205 transfers to the broadcast communication mode in thestep S313. On the other hand, the specific microcomputer waits for thesignal line CS to become high in the step S411 and ends the processing.

Thus, this embodiment properly switches the meaning (function) of thesignal transmitted through the signal line CS between the broadcastcommunication and the P2P communication. Thereby, the cameramicrocomputer 205, the lens microcomputer 111, and the adaptermicrocomputer 302 can communicate with one another with the small numberof signal lines (or channels).

[Authentication Communication Processing]

Referring now to FIGS. 9 and 10, a description will be given ofauthentication communication processing according to this embodiment.FIG. 9 illustrates signal waveforms in the authentication communicationprocessing performed among the camera microcomputer 205, the lensmicrocomputer 111, and the adapter microcomputer 302.

The top of the figure illustrates data communicated by the signal lineDATA, “Camera” indicates data output by the camera microcomputer 205,“Adapter” indicates data output by the adapter microcomputer 302, and“Lens” indicates data output from the microcomputer 111. “CS signal(camera)” indicates a signal output state (referred to as a CS signalstate hereinafter) of the signal line CS detected by the cameramicrocomputer 205, and “CS output (camera)” indicates a signal outputfrom the camera microcomputer 205 to the signal line CS. “CS signal(adapter)” indicates a CS signal state detected by the adaptermicrocomputer 302, and “CS output (adapter)” indicates a signal outputfrom the adapter microcomputer 302 to the signal line CS. “CS SW”indicates the state of the CS switch 3033 controlled by the adaptermicrocomputer 302, and Low indicates the connection state. “CS signal(lens)” indicates a CS signal state detected by the lens microcomputer111, and “CS output (lens)” indicates a signal output from the lensmicrocomputer 111 to the signal line CS.

A flowchart in FIG. 10 illustrates a flow of authenticationcommunication processing. This authentication communication processingis performed when the power supply starts from the camera body 200 tothe interchangeable lens 100 and the adapter 300 after the camera body200 detects the connection of the interchangeable lens 100 through alens detection switch 1123 provided in the camera body 200. At the startof the authentication communication processing, the camera microcomputer205 transmits an authentication start request command via the signalline DATA by the broadcast communication in the step S500. In otherwords, the authentication start communication is performed. Thisprocessing is performed as a preprocess for the authenticationcommunication by the camera microcomputer 205. At this time, the CSswitch 3033 is set to the connected state. The processing in thebroadcast communication and P2P communication performed later is asdescribed with reference to FIGS. 7A, 7B, 8A, and 8B. As describedabove, the adapter microcomputer 302 and the lens microcomputer 111output different signals (low and high) to the signal line CS betweenthe ongoing communication with the camera microcomputer 205 (from acommunication start to an end) and the communication standby in thebroadcast communication and the P2P communication.

The adapter microcomputer 302 and the lens microcomputer 111 that havereceived the authentication start request command perform receptionprocessing in the broadcast communication in the steps S506 and S513,respectively. If the received result is an authentication start requestcommand, the adapter microcomputer 302 switches the CS switch 3033 to adisconnected state in the step S507. Herein, the switching timing of theCS switch 3033 is after the adapter microcomputer 302 stops the lowoutput to the signal line CS (after the step S208 in FIG. 7B), but maybe just before or simultaneous with stopping the low output.

Next, the camera microcomputer 205 sends an authentication requestcommand via the communication line DATA in the step S501 when theadapter microcomputer 302 stops the low output to the signal line CS andthe communication circuit is waiting for the communication. In otherwords, the authentication request communication is performed. In thesubsequent processing, the camera microcomputer 205 performs theauthentication communication. The authentication request command isslave designation data for designating as a designated slave (specificaccessory apparatus) the communication slave that has received itthrough the broadcast communication. Since the communication line CS isdisconnected by the CS switch 3033 in the step S507, the low output tothe communication line CS in the step S501 is not detected by the lensmicrocomputer 111.

On the other hand, since the communication line DATA is connected, theauthentication request command has been transmitted to the lensmicrocomputer 111. However, the authentication request command is acommand premised on the broadcast communication in which data can bereceived only when the communication line CS is low. Hence, the lensmicrocomputer 111 that has received the authentication request commandwhile the communication line CS is high ignores this command.

The adapter microcomputer 302 receives the authentication requestcommand via the communication line DATA by the broadcast communicationin the step S508. Since the adapter microcomputer 302 that has receivedthe authentication request command has received the authenticationrequest command for the first time, it is the slave designation datatransmitted to itself, and determines that the next P2P communication iscommunication addressed to itself.

Next, in the step S502, the camera microcomputer 205 transmits an IDcommunication request command via the communication line DATA by the P2Pcommunication. In other words, the authentication informationcommunication is performed. At this time, the camera microcomputer 205does not recognize that the communication counterpart of the P2Pcommunication is the adapter microcomputer 302. This is because it isnot yet known at this point how many accessories are connected to thecamera body 200. The camera microcomputer 205 only knows that any of theconnected communication slaves responds to the P2P communication bydesignating the designated slave by the authentication request commandtransmitted in the step S501.

In the step S509, the adapter microcomputer 302 designated as thedesignated slave receives the ID communication request command by theP2P communication, and in response, sends its own ID information(authentication information) to the camera microcomputer 205 via thesignal line DATA by the P2P communication. Thereafter, the adaptermicrocomputer 302 switches the CS switch 3033 to the connected state inthe step S510. Herein, the switching timing of the CS switch 3033 isafter the adapter microcomputer 302 stops the low output to the signalline CS (after the step S410 in FIG. 8B), but it may be just before orsimultaneous with the stop of the low output.

The P2P communication in the steps S502 and S509 may be performed onlyin one reciprocation between the camera microcomputer 205 and theadapter microcomputer 302 as illustrated in FIG. 9 or may be performedin two or more reciprocations.

Furthermore, although the timing for switching the CS switch 3033 to theconnected state is after the step S509 in this flowchart, it may bebefore the step 509 (after the reception of the authentication requestcommand in the step S508). This is because the adapter microcomputer 302that has received the authentication request command by the broadcastcommunication recognizes that it is the slave designation data toitself, and the lens microcomputer 111 that has not received theauthentication request command does not recognize that it is the slavedesignation data to itself. Hence, even when the CS switch 3033 isswitched to the connected state after the step S508, only the adaptermicrocomputer 302 responds to the ID communication request command inthe step S509.

Next, when the adapter microcomputer 302 stops the low output to thesignal line CS and the communication circuit is waiting for thecommunication, the camera microcomputer 205 resends the authenticationrequest command via the communication line DATA by the broadcastcommunication in the step S503. Herein, since the communication line CSis connected, the adapter microcomputer 302 receives the authenticationrequest command in the step S511, and the lens microcomputer 111 alsoreceives it in the step S514. However, the adapter microcomputer 302 hasalready finished the communication (or the authentication) in responseto the authentication request command and the ID communication requestcommand, and thus ignores the authentication request command at thisstage. On the other hand, this is the first reception of theauthentication request command for the lens microcomputer 111, the lensmicrocomputer 111 interprets it as the slave designation data to itselfand prepares for the P2P communication.

Thereafter, the camera microcomputer 205 transmits the ID communicationrequest command via the communication line DATA by the P2P communicationin the step S504. Herein, the camera microcomputer 205 does notrecognize that the counterpart of the P2P communication is the lensmicrocomputer 111. This is because of the same reason as that for theadapter microcomputer 302. In the step S515, the lens microcomputer 111transmits its ID information (authentication information) to the cameramicrocomputer 205 via the signal line DATA by the P2P communication inresponse to the ID communication request command. When confirming thatthe received ID information is that of the interchangeable lens 100, thecamera microcomputer 205 determines that no further communication slaveto be authenticated is connected. Then, in the step S505, the cameramicrocomputer 205 transmits the authentication end request command forending the authentication communication processing via the signal lineDATA by the broadcast communication. In other words, the authenticationend communication is performed. In the steps S512 and 516, the adaptermicrocomputer 302 and the lens microcomputer 111 receive anauthentication end request command. Thereby, the authenticationcommunication processing ends.

Thus, in this embodiment, the camera microcomputer 205 sequentiallydesignates the designated slave using the broadcast communicationwhenever the CS output state indicates the ongoing standby of thecommunication, and performs the authentication communication using thebroadcast communication and the P2P communication.

[Authentication Communication Processing Including Sleep Processing]

A description will now be given of a sleep communication performedbetween the camera microcomputer 205 and the adapter microcomputer 302.The camera microcomputer 205 can shift the adapter 300 from the normaloperation state to the sleep state by transmitting a sleep requestcommand described later to the adapter microcomputer 302 using thebroadcast communication. The normal operation state of the adapter 300(adapter microcomputer 302) is an operation state for performingprocessing in response to transmission data such as a transmissionrequest command from the camera microcomputer 205, for example,transmissions of ID information and adapter data. In the followingdescription, the operation of the adapter 300 in the normal operationstate will be referred to as a normal operation.

On the other hand, the sleep state includes a first sleep state thatreturns to the normal operation state in response to a reception of thetransmission data from the camera microcomputer 205, and a second sleepstate that does not return to the normal operation state even when thetransmission data is received and performs no processing in response tothe transmission data. The second sleep state is maintained until thepower supply from the camera body 200 is stopped (cut off), and isreleased when the stopped power supply is resumed.

The camera microcomputer 205 can transmit to the adapter microcomputer302 a first sleep request command for shifting the adapter microcomputer302 from the normal operation state to the first sleep state and asecond sleep request command for shifting it to the second sleep state.When the camera microcomputer 205 determines that the normal processingof the adapter 300 is unnecessary, the camera microcomputer 205transmits the second sleep request command to the adapter microcomputer302 to prohibit the adapter 300 from performing the normal processing,and avoids the malfunctions and communication failures in the camerasystem.

Referring now to a flowchart in FIG. 11, a description will be given ofauthentication communication processing including processing in whichthe camera microcomputer 205 shifts the adapter 300 (adaptermicrocomputer 302) from the normal operation state to the second sleepstate. Processing from S600 to S602 is the same as the processing fromS500 to S502 shown in FIG. 10, and a description thereof will beomitted.

In S603, the camera microcomputer 205 determines whether the adapter 300is compatible with the camera body 200, based on the ID informationacquired from the adapter 300 (adapter microcomputer 302) in S602. Inother words, it determines whether or not the adapter 300 cancommunicate with the camera body 200 or can perform processing inresponse to a request command from the camera body 200. The cameramicrocomputer 205 proceeds to S609 if the adapter 300 is an incompatibleadapter (incompatible accessory apparatus) that is not compatible withthe camera body 200, and proceeds to S604 if the adapter 300 is acompatible adapter (compatible accessory apparatus). Thus, the cameramicrocomputer 205 specifies the adapter 300 as a sleep target accessoryapparatus based on the ID information acquired from the adapter 300.Processing of S604 and S605 is the same as the processing of S503 andS504 shown in FIG. 10, respectively, and a description thereof will beomitted.

Next, in S606, the camera microcomputer 205 determines whether the totalnumber of all accessory apparatuses (the interchangeable lens 100 andthe adapter 300) connected to the camera body 200 is equal to or morethan a predetermined number. If the total number of accessoryapparatuses is equal to or more than the predetermined number, thecamera microcomputer 205 proceeds to S609, and if not, proceeds to S607.

In S607, the camera microcomputer 205 determines whether the number ofoccurrences of communication errors is equal to or more than apredetermined number. The communication error occurs due to thedisconnection of the communication line or the voltage noise. Thecommunication having a format different from the predetermined formatmay be determined to be an error. The camera microcomputer 205 proceedsto S609 when the number of communication errors is equal to or more thanthe predetermined number, and proceeds to S608 when the number is lessthan the predetermined number. The processing of S608 is the same as theprocessing of S505 shown in FIG. 10, and a description thereof will beomitted. The camera microcomputer 205 that has completed the processingof S608 ends the authentication communication processing.

In S609, the camera microcomputer 205 transmits the second sleep requestcommand to the adapter 300 (adapter microcomputer 302) as the sleeptarget accessory apparatus through the broadcast communication (firstcommunication). Thereby, the adapter microcomputer 302 shifts from thenormal operation state to the second sleep state after displaying orperforming the user notification for notifying the user of shifting tothe second sleep state in S610.

Next, in S611, the camera microcomputer 205 notifies the user that theadapter 300 has shifted to the second sleep state through the displayunit 206 in the camera body 200 or by an audio output from anunillustrated speaker. Due to this user notification and the usernotification by the adapter 300 in S609, the user can realize a cause ofthe operational failure of the adapter 300. In other words, the user canlearn that the adapter 300 is incompatible with the camera body 200 or anumber of adapters exceeding the permissible number (predeterminednumber) are attached to the camera body 200. Thus, the authenticationcommunication processing ends.

As described above, this embodiment transmits the second sleep requestcommand through the broadcast communication. Therefore, when a pluralityof adapters are attached to the camera body 200 in a connected state, asdescribed later, all of these adapters shift to the second sleep state.However, when the authentication communication is performed and thesignal line CS is disconnected, the second sleep request command may betransmitted only to some of the plurality of adapters that are close tothe camera body 200 so as to shift them to the second sleep state. Inother words, the adapter that has received the second sleep requestcommand gets connected to the signal line CS before shifting to thesleep state. Thereby, the camera microcomputer 205 can communicate withthe adapter closer to the interchangeable lens 100 than the adapter thathas shifted to the sleep state. Thus, the camera microcomputer 205 canperform the authentication start communication when it would like totransmit the sleep request command to only some of the plurality ofadapters close to the camera body 200.

According to the first embodiment described above, the camera systemthat performs communications using two lines (two channels) or thesignal line CS and the signal line DATA makes an authenticationcommunication in order from the accessory apparatus closer to the camerabody 200 by switching the CS switch 3033 provided in the adapter 300.Finally, the authentication communication with the interchangeable lenscan be performed. Thereby, even when a plurality of accessoryapparatuses are connected to the camera body 200, the authenticationcommunication can be performed in a short time.

Moreover, when the adapter 300 is the incompatible adapter, or when anumber of adapters exceeding the permissible number are attached to thecamera body 200 or the communication errors frequently occur, theadapter can be shifted to the second sleep state even when it receivesthe data transmission. In other words, the normal operation of theadapter as the sleep target accessory apparatus can be prohibited. Thus,it is possible to avoid malfunctions, communication failures, and thelike in the camera system including the sleep target accessoryapparatus.

[Variation]

Next follows a description of a variation of the first embodiment. Thefirst embodiment has described a case where the adapter 300 (the adaptermicrocomputer 302) is shifted to the first and second sleep states inthe authentication communication among the camera microcomputer 205, theadapter microcomputer 302, and the lens microcomputer 111. However, theadapter 300 may be shifted to the first and second sleep states in acommunication other than authentication communication among the cameramicrocomputer 205, the adapter microcomputer 302, and the lensmicrocomputer 111. In other words, when the camera microcomputer 205performs the authentication communication or another specificcommunication while sequentially specifying the adapter microcomputer302 and the lens microcomputer 111, it may shift the adapter 300 to thefirst and second sleep states.

ID information as the authentication information transmitted from theadapter microcomputer 302 and the lens microcomputer 111 to the cameramicrocomputer 205 in response to the ID communication request commandmay include information of a serial number for each type of accessoryapparatus (such as 00 for the interchangeable lens and 01 for theextender). Moreover, the ID information may include information to whichthe meaning was allocated for every bit. It may contain information of aplurality of bytes. The ID information may be information indicating thetype and function of the accessory apparatus.

The above authentication communication processing has described that thecamera microcomputer 205 confirms that the ID information belongs to theinterchangeable lens 100 and determines the end of the authenticationcommunication. Alternatively, the ID information may include informationindicating the interchangeable lens and information for instructing theend of the authentication communication, and the camera microcomputer205 may detect it and determine the end of the authenticationcommunication. In addition to the ID information communication, aconfirmation communication for asking the communication slave aboutwhether or not the authentication communication can be terminated may beseparately performed by the P2P communication before and after the IDcommunication.

The first embodiment has described a single adapter 300 connectedbetween the camera body 200 and the interchangeable lens 100, but allowsa plurality of adapters connected in series. Even when a plurality ofadapters are thus connected, it is possible to authenticate each adapterand the interchangeable lens 100 in a short time in the same procedureas that described in the first embodiment. At this time, the pluralityof adapters that simultaneously receive the authentication start requestcommand by the broadcast communication almost simultaneously set the CSswitch to the disconnected state. Therefore, the subsequentauthentication is always performed sequentially from the adapter closerto the camera body 200 one by one. Similar to the case where one adapteris connected, the interchangeable lens 100 is finally authenticated, anda series of authentication communication processing is completed.

When a plurality of adapters are connected and the same ID informationis received from the plurality of adapters as described above (forexample, when the user connects two adapters of the same model bymistake), the camera microcomputer 205 shifts one or all of the adaptersto the second sleep state. This is because the camera microcomputer 205cannot identify the adapter as the communication counterpart in thiscase, and cannot continue the communication with the adapter.

When the adapter 300 is not connected and the interchangeable lens 100is directly connected to the camera body 200, the authenticationcommunication is performed for the interchangeable lens 100 withoutperforming part of the authentication communication for the adapter 300in the authentication communication processing illustrated in FIGS. 9and 10.

The adapter 300 in the first embodiment may be an extender as describedabove, an adapter including a drivable optical element (such as a focuslens, a diaphragm, and an image stabilization lens), or an adapterincluding a variety of sensors (a phase difference sensor, an angularvelocity).

According to the description in the first embodiment, the cameramicrocomputer 205 can transmit to the adapter microcomputer 302 thefirst sleep request command for shifting the adapter 300 to the firstsleep state, and the second sleep request command for shifting theadapter 300 to the second sleep state. However, the camera microcomputer205 may transmit only the second sleep request command to the adaptermicrocomputer 302.

The camera microcomputer 205 may shift only a specific one of all theaccessory apparatuses connected to the camera body 200 to the secondsleep state by transmitting the sleep request command through the P2Pcommunication. At this time, one of the first and second sleep states tobe transferred may be selected according to the timing at which theadapter microcomputer 302 receives the sleep request command. Thereby,even if the camera microcomputer 205 can transmit only a single sleeprequest command, the adapter 300 can shift to the first and second sleepstates.

The adapter microcomputer 302 may set the shifting timing to the secondsleep state to a period from receiving the authentication startcommunication (starting the authentication communication) to receivingthe authentication end communication (completing the authenticationcommunication). Thereby, the camera microcomputer 205 that has receivedthe authentication information can quickly shift the adapter 300 to thesecond sleep state.

The first embodiment has described the camera system having the signaltransmission channel and the data communication channel. However, thepresent invention covers a camera system having only the datacommunication channel and configured to transmit the second sleeprequest command from the camera body to the adapter to shift the adapterfrom the normal operation state to the second sleep state.

OTHER EMBODIMENTS

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

The present invention can prohibit the sleep target accessory apparatusfrom performing processing in response to transmission data from thecamera, and avoid malfunctions or communication failures in the imagepickup system.

What is claimed is:
 1. A camera usable while one or more accessoryapparatuses are connected to the camera, the camera comprising: a cameracommunication unit connected to a data communication channel used for adata communication between the camera and the one or more accessoryapparatuses; and a camera controller configured to perform the datacommunication with the one or more accessory apparatuses via the datacommunication channel, wherein the camera controller transmits to atleast one sleep target accessory apparatus among the one or moreaccessory apparatuses which are selected based on authenticationinformation, a sleep request command for shifting the sleep targetaccessory apparatus from an operation state for performing processing inresponse to a data transmission from the camera to a sleep state thatdoes not perform the processing regardless of the data transmission,wherein the camera controller: performs, as the data communication, afirst communication that is a communication without designation ofcommunication counterpart and a second communication that is acommunication between the camera and a specific accessory apparatus as adesignated communication counterpart; and transmits the sleep requestcommand to the sleep target accessory apparatus through the firstcommunication, wherein the camera communication unit is connected to asignal transmission channel provided separately from the datacommunication channel, and used to transmit a signal between the cameraand the one or more accessory apparatuses, and wherein the cameracontroller: performs an authentication communication with the specificaccessory apparatus using the first communication and the secondcommunication whenever receiving a signal indicating an ongoing standbyof the first communication from each accessory apparatus via the signaltransmission channel, while sequentially designating the specificaccessory apparatus using the first communication, and specifies thesleep target accessory apparatus based on the authentication informationobtained from each specific accessory apparatus by the authenticationcommunication.
 2. The camera according to claim 1, wherein theprocessing is a data transmission to the camera.
 3. The camera accordingto claim 1, wherein the sleep request command is a command that causesthe sleep target accessory apparatus to maintain the sleep state untilpower supply from the camera is stopped.
 4. The camera according toclaim 3, wherein the camera controller returns the sleep targetaccessory apparatus to the operation state by resuming the power supply.5. The camera according to claim 1, wherein the camera controllertransmits the sleep request command to the sleep target accessoryapparatus when the number of accessory apparatuses is larger than apredetermined number.
 6. The camera according to claim 1, wherein thecamera controller transmits the sleep request command to the sleeptarget accessory apparatus when the number of communication errorsgenerated with the sleep target accessory apparatus is larger than apredetermined number.
 7. The camera according to claim 1, wherein thecamera controller notifies a user that the sleep target accessoryapparatus has shifted to the sleep state.
 8. The camera according toclaim 1, wherein the one or more accessory apparatuses include aninterchangeable lens apparatus, and an adapter apparatus connectedbetween the interchangeable lens apparatus and the camera, and whereinthe sleep target accessory apparatus is the adapter apparatus.
 9. Anaccessory apparatus connectable to a camera usable while one or moreaccessory apparatuses are connected to the camera, the accessoryapparatus comprising: an accessory communication unit connected to adata communication channel used for a data communication between thecamera and the one or more accessory apparatuses; and an accessorycontroller configured to performs the data communication with the cameravia the data communication channel, wherein when receiving a sleeprequest command transmitted from the camera based on authenticationinformation of the accessory apparatus, the accessory controller shiftsfrom an operation state for performing processing in response to a datatransmission from the camera to a sleep state that does not perform theprocessing regardless of the data transmission, wherein the accessorycontroller: performs, as the data communication, a first communicationthat is a communication without designation of communication counterpartand a second communication that is a communication between the cameraand the accessory apparatus as a designated communication counterpart;and receives the sleep request command through the first communication,wherein the accessory communication unit is connected to a signaltransmission channel provided separately from the data communicationchannel, and used to transmit a signal between the camera and the one ormore accessory apparatuses, and wherein the accessory controller:outputs a signal indicating an ongoing standby of the firstcommunication to the signal transmission channel, and performs anauthentication communication with the camera using the firstcommunication and the second communication when designated as thespecific accessory apparatus using the first communication from thecamera that has received the signal.
 10. The accessory apparatusaccording to claim 9, wherein the processing is a data transmission tothe camera.
 11. The accessory apparatus according to claim 9, whereinthe accessory controller maintains the sleep state until power supplyfrom the camera is stopped.
 12. The accessory apparatus according toclaim 11, wherein the accessory controller returns to the operationstate when the power supply is resumed.
 13. The accessory apparatusaccording to claim 9, wherein the accessory controller notifies a userthat the accessory controller has shifted to the sleep state.
 14. Theaccessory apparatus according to claim 9, wherein the one or moreaccessory apparatuses include an interchangeable lens apparatus, and anadapter apparatus connected between the interchangeable lens apparatusand the camera, and wherein each accessory apparatus is the adapterapparatus.
 15. A control method for a camera usable while one or moreaccessory apparatuses are connected to the camera and configured toperform a data communication with the one or more accessory apparatusesvia a data communication channel, the control method comprising thesteps of: causing the camera to acquire authentication information fromthe one or more accessory apparatuses; and causing the camera totransmit to at least one sleep target accessory apparatus among the oneor more accessory apparatuses which are selected based on theauthentication information, a sleep request command for shifting thesleep target accessory apparatus from an operation state for performingprocessing in response to a data transmission from the camera to a sleepstate that does not perform the processing regardless of the datatransmission, wherein the control method further includes the steps of:causing the camera to perform, as the data communication, a firstcommunication that is a communication without designation ofcommunication counterpart and a second communication that is acommunication between the camera and a specific accessory apparatus as adesignated communication counterpart; and causing the camera to transmitthe sleep request command to the sleep target accessory apparatusthrough the first communication, wherein a signal transmission channelis provided separately from the data communication channel, and used totransmit a signal between the camera and the one or more accessoryapparatuses, and wherein the control method further includes the stepsof: causing the camera to perform an authentication communication withthe specific accessory apparatus using the first communication and thesecond communication whenever receiving a signal indicating an ongoingstandby of the first communication from each accessory apparatus via thesignal transmission channel, while sequentially designating the specificaccessory apparatus using the first communication, and causing thecamera to specify the sleep target accessory apparatus based on theauthentication information obtained from each specific accessoryapparatus by the authentication communication.
 16. A control method foran accessory apparatus connectable to a camera usable while one or moreaccessory apparatuses are connected to the camera, and configured toperform a data communication with the camera via a data communicationchannel, the control method comprising the steps of: causing theaccessory apparatus to transmit authentication information; and causingthe accessory apparatus to shift, when receiving a sleep request commandtransmitted from the camera based on the authentication information ofthe accessory apparatus, from an operation state for performingprocessing in response to a data transmission from the camera to a sleepstate that does not perform the processing regardless of the datatransmission, wherein the control method further includes the steps of:causing the accessory apparatus to perform, as the data communication, afirst communication that is a communication without designation ofcommunication counterpart and a second communication that is acommunication between the camera and the accessory apparatus as adesignated communication counterpart; and causing the accessoryapparatus to receive the sleep request command through the firstcommunication, wherein a signal transmission channel is providedseparately from the data communication channel, and used to transmit asignal between the camera and the one or more accessory apparatuses, andwherein the control method further includes the steps of: causing theaccessory apparatus to output a signal indicating an ongoing standby ofthe first communication to the signal transmission channel, and causingthe accessory apparatus to perform an authentication communication withthe camera using the first communication and the second communicationwhen designated as the specific accessory apparatus using the firstcommunication from the camera that has received the signal.
 17. Anon-transitory computer-readable storage medium that stores a controlprogram that causes a computer in a camera usable while one or moreaccessory apparatuses are connected to the camera, to operate inaccordance with the control method according to claim
 15. 18. Anon-transitory computer-readable storage medium that stores a controlprogram that causes a computer in an accessory apparatus connectable toa camera usable while one or more accessory apparatuses are connected tothe camera, to operate in accordance with the control method accordingto claim 16.